Binding of transducin and transducin-derived peptides to rhodopsin studies by attenuated total reflection-Fourier transform infrared difference spectroscopy

Fourier transform infrared difference spectroscopy combined with the attenuated total reflection technique allows the monitoring of the association of transducin with bovine photoreceptor membranes in the dark. Illumination causes infrared absorption changes linked to formation of the light-activated rhodopsin-transducin complex. In addition to the spectral changes normally associated with meta II formation, prominent absorption increases occur at 1735 cm-1, 1640 cm-1, 1550 cm-1, and 1517 cm-1. The D2O sensitivity of the broad carbonyl stretching band around 1735 cm-1 indicates that a carboxylic acid group becomes protonated upon formation of the activated complex. Reconstitution of rhodopsin into phosphatidylcholine vesicles has little influence on the spectral properties of the rhodopsin-transducin complex, whereas pH affects the intensity of the carbonyl stretching band. AC-terminal peptide comprising amino acids 340-350 of the transducin alpha-subunit reproduces the frequencies and isotope sensitivities of several of the transducin-induced bands between 1500 and 1800 cm-1, whereas an N-terminal peptide (aa 8-23) does not. Therefore, the transducin-induced absorption changes can be ascribed mainly to an interaction between the transducin-alpha C-terminus and rhodopsin. The 1735 cm-1 vibration is also seen in the complex with C-terminal peptides devoid of free carboxylic acid groups, indicating that the corresponding carbonyl group is located on rhodopsin.

Spectroscopic evidence for altered chromophore--protein interactions in low-temperature photoproducts of the visual pigment responsible for congenital night blindness

The replacement of Gly90 by Asp in human rhodopsin causes congenital night blindness. It has been suggested that the molecular origin for the trait is an altered electrostatic environment of the protonated retinal Schiff base chromophore. We have investigated the corresponding recombinant bovine rhodopsin mutant G90D, as well as the related mutants E113A and G90D/E113A, using spectroscopy at low temperature. This allows the assessment of chromophore-protein interactions under conditions where conformational changes are mainly restricted to the retinal-binding site. Each of the mutant pigments formed bathorhodopsin- and isorhodopsin-like intermediates, but the concomitant visible absorption changes reflected differences in the electrostatic environment of the protonated Schiff base in each pigment. Fourier transform infrared-difference spectroscopy revealed effects on the chromophore fingerprint and hydrogen-out-of-plane vibrational modes, which were indicative of the removal of an electrostatic perturbation near C12 of the retinal chromophore in all three mutants. A comparison of the UV-visible and infrared-difference spectra of the mutant pigments strongly suggests that Glu113 is stably protonated in G90D. The corresponding carbonyl-stretching mode is assigned to a band at 1727 cm-1. In contrast to the case in native bathorhodopsin, the all-trans-retinal chromophores in the primary photoproducts of the mutant pigments are essentially relaxed. The peptide carbonyl vibrational changes in mutants G90D and G90D/ E113A suggest that this is due to a more flexible retinal-binding site. Therefore, the steric strain exerted on the chromophore in native bathorhodopsin may be caused by electrostatic forces that specifically involve glutamate 113.

Characterization of the mutant visual pigment responsible for congenital night blindness: a biochemical and Fourier-transform infrared spectroscopy study

A mutation in the gene for the rod photoreceptor molecule rhodopsin causes congenital night blindness. The mutation results in a replacement of Gly90 by an aspartic acid residue. Two molecular mechanisms have been proposed to explain the physiology of affected rod cells. One involves constitutive activity of the G90D mutant opsin [Rao, V. R., Cohen, G. B., & Oprian, D. D. (1994) Nature 367, 639-642]. A second involves increased photoreceptor noise caused by thermal isomerization of the G90D pigment chromophore [Sieving, P. A., Richards, J. E., Naarendorp F., Bingham, E. L., Scott, K., & Alpern, M. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 880-884]. Based on existing models of rhodopsin and in vitro biochemical studies of site-directed mutants, it appears likely that Gly90 is in the immediate proximity of the Schiff base chromophore linkage. We have studied in detail the mutant pigments G90D and G90D/E113A using biochemical and Fourier-transform infrared (FTIR) spectroscopic methods. The photoproduct of mutant pigment G90D, which absorbs maximally at 468 nm and contains a protonated Schiff base linkage, can activate transducin. However, the active photoproduct decays rapidly to opsin and free all-trans-retinal. FTIR studies of mutant G90D show that the dark state of the pigment has several structural features of metarhodopsin II, the active form of rhodopsin. These include a protonated carboxylic acid group at position Glu113 and increased hydrogen-bond strength of Asp83. Additional results, which relate to the structure of the active G90D photoproduct, are also reported. Taken together, these results may be relevant to understanding the molecular mechanism of congenital night blindness caused by the G90D mutation in human rhodopsin.

Photoactivated state of rhodopsin and how it can form

A variety of spectroscopic and biochemical studies of the photoreceptor rhodopsin have revealed conformation changes which occur upon its photoactivation. Assignment of these molecular alterations to specific regions in the receptor has been attempted by studying native opsin regenerated with synthetic retinal analogs or recombinant opsins regenerated with 11-cis retinal. We propose a model for the photoactivation mechanism which defines 'off' and 'on' states for individual molecular groups. These groups have been identified to undergo structural alterations during photoactivation. Analysis of mutant pigments in which specific groups are locked into their respective 'on' or 'off' states provides a framework to identify determinants of the active conformation as well as the minimal number of intramolecular transitions to switch to this conformation. The simple model proposed for the active-state of rhodopsin can be compared to structural models of its ground-state to localize chromophore-protein interactions that may be important in the photoactivation mechanism.

A mutant rhodopsin photoproduct with a protonated Schiff base displays an active-state conformation: a Fourier-transform infrared spectroscopy study

In the rhodopsin mutant E113A/A117E the position of the protonated Schiff base counterion, Glu113, is moved by one helix turn from position 113 to 117. The photoreaction of this mutant pigment was studied by Fourier-transform infrared (FTIR) difference spectroscopy. At acidic pH, formation of a 474-nm absorbing photoproduct previously characterized biochemically as a species that activates transducin caused infrared absorption changes typical of metarhodopsin II (MII) formation in native rhodopsin. Specific spectral alterations revealed a localized perturbation near the protonated Schiff base in the dark state. In addition, an infrared band assigned to the C = O stretching vibration of Glu113 in MII of rhodopsin was abolished in the mutant. Absorption changes caused by Asp83 and Glu122 C = O stretching vibrations characteristic of rhodopsin MII formation were not affected. At alkaline pH, mutant E113A/A117E formed predominantly a 382-nm absorbing photoproduct. It displayed infrared-difference absorption bands significantly different from those of native MII over a large spectral range. These results support the conclusion that the 474-nm photoproduct of mutant E113A/A117E, despite a protonated Schiff base linkage, displays a predominantly MII-like conformation capable of catalyzing guanine-nucleotide exchange by transducin.

A conserved carboxylic acid group mediates light-dependent proton uptake and signaling by rhodopsin

A carboxylic acid residue is conserved at the cytoplasmic border of the third transmembrane segment among nearly all G protein-coupled receptors. In the visual receptor rhodopsin, replacement of the conserved Glu134 by a neutral glutamine results in enhanced transducin activation. Here we show that a key event in forming the active state of rhodopsin is proton uptake by Glu134 in the metarhodopsin II (MII) photoproduct. Site-directed mutants E134D and E134Q were studied by flash photolysis, where formation rates of their photoproducts and rates of pH change could be monitored simultaneously. Both mutants showed normal MII formation rates. However, E134D displayed a slowed rate of proton uptake and E134Q displayed a loss of light-induced uptake of two protons from the aqueous phase. Thus, Glu134 mediates light-dependent proton uptake by MII. We propose that receptor activation requires a light-induced conformational change that allows protonation of Glu134 and subsequent protonation of a second group. The strong conservation of Glu134 in G protein-coupled receptors implies a general requirement for a proton acceptor group at this position to allow light- or ligand-dependent receptor activation.

Identification of glutamic acid 113 as the Schiff base proton acceptor in the metarhodopsin II photointermediate of rhodopsin

In order to investigate the molecular mechanism of rhodopsin photoactivation, site-directed mutants of bovine rhodopsin were studied by Fourier-transform infrared (FTIR) difference spectroscopy. Rhodopsin mutants E113D and E113A were prepared in which the retinylidene Schiff base counterion, Glu113, was replaced by Asp and Ala, respectively. FTIR difference spectra were recorded and compared with spectra of recombinant native rhodopsin. Both mutant pigments formed photoproducts at 0 degrees C with vibrational absorption bands typical of the metarhodopsin II (MII) state of rhodopsin. The FTIR difference spectrum of E113D was nearly identical to that of rhodopsin. A positive band at 1712 cm-1 caused by the protonation of an internal carboxylic acid in rhodopsin was shifted slightly to 1709 cm-1 in mutant E113D. E113A was studied at acidic pH in the presence of chloride as an inorganic counterion to the protonated Schiff base. The 1712-cm-1 (1709-cm-1) band was absent in the FTIR difference spectrum of mutant E113A. Therefore, we have assigned the 1712-cm-1 absorbance band to the C = O stretching vibration of protonated Glu113 in MII of rhodopsin. These results show that the Schiff base counterion of rhodopsin, the carboxylate side chain of Glu113, becomes protonated during MII formation.

Characterization of rhodopsin-transducin interaction: a mutant rhodopsin photoproduct with a protonated Schiff base activates transducin

Rhodopsin, a G protein-coupled seven-transmembrane helix receptor, contains an 11-cis-retinal chromophore covalently linked to opsin apoprotein by a protonated Schiff base. Photoisomerization of the chromophore followed by Schiff base deprotonation forms metarhodopsin II (MII, lambda max = 380 nm), the active state (R*) that catalyzes guanine nucleotide exchange in transducin, the G protein of the photoreceptor cell. Schiff base deprotonation is required for R* formation. The Schiff base positive charge in rhodopsin is stabilized by a carboxylic acid counterion, Glu113. The position of the carboxylate counterion was moved by one helix turn to position 117 by site-specific mutagenesis. Photolysis of the mutant pigment E113A/A117E (lambda max = 491 nm) resulted in a mixture of two photoproducts: (1) an MII-like form with an unprotonated Schiff base (lambda max = 382 nm) favored at alkaline pH; and (2) a photoproduct with a protonated Schiff base (lambda max = 474 nm), spectroscopically similar to metarhodopsin I, favored at acidic pH. Here, we have studied the interactions between the mutant E113A/A117E photoproducts and transducin in detail. Transducin slowed down thermal conversion of the 474 nm form to the 382 nm form by stabilizing the 474 nm photoproduct. This effect was maximal at the pH optimum of transducin activation by the mutant R* and was abolished in the presence of GTP gamma S. In addition, the amount of the 474 nm species correlated with transducin activation rates during the thermal conversion of the photoproduct mixture. Thus, the 474 nm photoproduct of the mutant pigment, which contained a protonated Schiff base, activated transducin.(ABSTRACT TRUNCATED AT 250 WORDS)

Protonation states of membrane-embedded carboxylic acid groups in rhodopsin and metarhodopsin II: a Fourier-transform infrared spectroscopy study of site-directed mutants

A method was developed to measure Fourier-transform infrared (FTIR) difference spectra of detergent-solubilized rhodopsin expressed in COS cells. Experiments were performed on native bovine rhodopsin, rhodopsin expressed in COS cells, and three expressed rhodopsin mutants with amino acid replacements of membrane-embedded carboxylic acid groups: Asp-83-->Asn (D83N), Glu-122-->Gln (E122Q), and the double mutant D83N/E122Q. Each of the mutant opsins bound 11-cis-retinal to yield a visible light-absorbing pigment. Upon illumination, each of the mutant pigments formed a metarhodopsin II-like species with maximal absorption at 380 nm that was able to activate guanine nucleotide exchange by transducin. Rhodopsin versus metarhodopsin II-like photoproduct FTIR-difference spectra were recorded for each sample. The COS-cell rhodopsin and mutant difference spectra showed close correspondence to that of rhodopsin from disc membranes. Difference bands (rhodopsin/metarhodopsin II) at 1767/1750 cm-1 and at 1734/1745 cm-1 were absent from the spectra of mutants D83N and E122Q, respectively. Both bands were absent from the spectrum of the double mutant D83N/E122Q. These results show that Asp-83 and Glu-122 are protonated both in rhodopsin and in metarhodopsin II, in agreement with the isotope effects observed in spectra measured in 2H2O. A photoproduct band at 1712 cm-1 was not affected by either single or double replacements at positions 83 and 122. We deduce that the 1712 cm-1 band arises from the protonation of Glu-113 in metarhodopsin II.

Light-dependent transducin activation by an ultraviolet-absorbing rhodopsin mutant

The photoactivation pathway of an ultraviolet-absorbing rhodopsin mutant was studied. The mutant pigment, in which the retinylidene Schiff base counterion, Glu113, was replaced by glutamine (E113Q), was known to exist in a pH-dependent equilibrium between spectral forms absorbing at about 380 and 490 nm. The 380-nm form contains an unprotonated Schiff base chromophore linkage, whereas the 490-nm form contains a protonated Schiff base chromophore linkage. The role of the Schiff base proton in photoactivation was investigated by measuring transducin activation as a function of photoactivation wavelength. The transducin activation action spectra of rhodopsin and of mutant E113Q were found to be very similar to their UV-visible absorption spectra. Thus, the 380-nm UV form of the mutant E113Q could be activated directly by UV light to catalyze nucleotide exchange by transducin. The quantum efficiency of photoactivation of the UV-absorbing form of E113Q was similar to that of its visible-absorbing form. These results show that the presence of a protonated Schiff base in the ground state is not necessarily required for efficient photoactivation of visual pigments. They support the hypothesis that the key role of the protonated Schiff base in visible-absorbing pigments is to stabilize the ground state and to allow absorbance at wavelengths above about 420 nm. The findings are also consistent with transducin activation studies of mutant apoproteins regenerated with all-trans-retinal, or of mutant apoproteins alone, suggesting that the active state of rhodopsin can be formed via a number of pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of the rhodopsin-transducin interaction by a highly conserved carboxylic acid group

Rhodopsin is a member of a family of G protein-coupled receptors which share structural and functional homologies. A tripeptide sequence (Glu or Asp/Arg/Tyr) at the cytoplasmic border of the third transmembrane segment is conserved among most of these receptors. This region is involved in G protein activation in rhodopsin as well as in other receptors. The role of the conserved Glu-134 was studied by site-specific mutagenesis of rhodopsin in combination with a real-time fluorescence assay of G protein (transducin) activation. Assay conditions were chosen under which the transducin activation rate was determined either by rhodopsin-transducin complex formation or by GTP gamma S-induced complex dissociation. Glu-134 was replaced by Gln in order to mimic the protonated state of the carboxylic acid group. This mutation caused the pH dependency of complex formation to extend to the alkaline range as compared with rhodopsin. Replacement of Glu-134 by Asp had an opposite but less pronounced effect on the pH dependency and lowered the overall efficiency of transducin activation. The acidity constant (pKa) of the residue at position 134 did not directly determine the pH sensitivity of complex formation, indicating that other amino acid residues contribute to a titratable binding domain that includes Glu-134. In contrast, the pH sensitivity of GTP gamma S-induced complex dissociation was not changed by the mutations, although absolute rates were affected. The data suggest that the protonated state of Glu-134 favors binding of rhodopsin to transducin and that Glu-134 is not titratable in the rhodopsin-transducin complex.

Aspartic acid-212 of bacteriorhodopsin is ionized in the M and N photocycle intermediates: an FTIR study on specifically 13C-labeled reconstituted purple membranes

Purple membrane was regenerated from the denatured proteolytic (protease V8) fragments V-1 and V-2 of bacteriorhodopsin (BR), native membrane lipids, and all-trans-retinal. FTIR difference spectra of M and N intermediates of the reconstituted system are in close correspondence to those obtained from native BR. Asp-212 is the only internal aspartic acid in the V-2 fragment (helices F and G). Reconstituting a V-2 fragment from a [4-13C]Asp-labeled BR preparation with an unmodified V-1 fragment and vice versa have allowed us to assign IR bands to either Asp-212 or any of the remaining aspartic acids on V-1 (helices A-E). A carboxylate vibration at 1392 cm-1 has been identified in the M and N intermediates and assigned to Asp-212. Since no contribution of this residue to C = O stretches of protonated carboxyl groups was detected, Asp-212 must be ionized in light-adapted BR as well. The effect of [4-13C]Asp labeling of V-1 revealed a carboxylate vibration at 1385 cm-1 in light-adapted BR. Since Asp-96 and Asp-115 are protonated, this band is caused by Asp-85. All absorption changes of C = O stretches of protonated carboxyl groups are due to Asp residues on V-1. Correspondingly, the proton acceptor for Schiff base deprotonation in M is located on V-1, and must be Asp-85 (the only ionized Asp on V-1). The band assignments are compared with those reported for BR mutants, and the potential role of Asp-212 for proton translocation is discussed.

Serum and endometrial copper, zinc, iron and cobalt with inert and copper-containing IUCDs

Serum and endometrial copper (Cu), zinc (Zn), iron (Fe) and serum cobalt (Co) were measured in the mid-follicular and mid-luteal phases of the menstrual cycles in 30 Lippes loops users, 30 CuT-200 IUCD users and 24 matched controls by atomic absorption spectrophotometry. In the control group, there was no statistically significant difference in mean mid-luteal, compared to mid-follicular, levels of serum Cu, Zn, Fe and Co and endometrial Zn. Mid-luteal endometrium contained significantly higher mean Cu, and lower mean Fe levels. In Lippes loop users, compared to controls, the only statistically significant differences were lower mean mid-follicular serum Zn, lower mean endometrial Zn and Fe, and higher mean mid-luteal endometrial Fe. In CuT-200 users, compared to controls, there was significantly higher mean mid-follicular serum Zn and lower mean mid-luteal serum Co, higher mean mid-follicular endometrial Cu and lower mean mid-follicular endometrial Fe levels. Compared to Lippes loop, CuT-200 users had significantly higher mean mid-follicular serum Co and endometrial Cu and Zn, and lower mean mid-follicular endometrial Fe.

Serum and endometrial sodium and potassium levels with inert and copper-containing IUCDs and relation to serum steroid levels

Serum and endometrial sodium (Na) and potassium (K) levels and serum estradiol, progesterone, testosterone and cortisol were measured in the mid-follicular and mid-luteal phases of the menstrual cycle in 20 Lippes loop and 20 CuT-200 IUCD users and 20 matched controls. Na and K were measured by atomic absorption spectrophotometry, while serum steroids were measured by RIA. Regarding steroids, the only significant difference between the three groups was a significantly lower mean mid-luteal serum estradiol in CuT-200 IUCD users compared to Lippes loop users (p less than 0.05). Regarding sodium in the control group, there was significantly lower mean mid-luteal serum and endometrial Na (p less than 0.01) that was not found in both groups of IUCD users. In the mid-follicular phase, there was significantly higher mean serum Na in both Lippes loop and CuT-200 groups compared to controls (p less than 0.05). Mean endometrial Na showed no significant difference between the three groups in both phases of the menstrual cycle. Regarding potassium in the control group, there was significantly lower mean levels in the mid-luteal-phase of the cycle (p less than 0.01) that was not seen with both groups of IUCD users. Serum K showed no significant difference in the three groups in both phases of the menstrual cycle. Endometrial K showed a significantly higher mean level in both Lippes loop and CuT-200 IUCD users compared to controls in the mid-luteal (p less than 0.01), but not in the mid-follicular phases of the cycle.

Effect of depo-medroxyprogesterone acetate on coagulation factors and serum lipids in Egyptian women

The short-term (3 months) and long-term (15 months) effect of DMPA contraception on various coagulation parameters (predictive of thrombosis) and on serum lipids (predictive of atherosclerosis) were prospectively studied in 30 Egyptian women, compared to their pretreatment levels. There were no significant changes in all the coagulation parameters studied after 3 months, and there was only a significant reduction in antithrombin III (AT III) level after 15 months (p less than 0.01). Concerning serum lipids, after 3 months, there were no significant changes in total lipids (TL), total cholesterol (TC) and triglycerides (Tg), while there was a significant decrease in high density lipoprotein cholesterol (HDL-C) (p less than 0.001), and a significant increase in low density lipoprotein cholesterol (LDL-C) (p less than 0.01). After 15 months there was a significant increase in TL, TC and LDL-C (p less than 0.001) and a significant decrease in HDL-C (p less than 0.001). Lipoprotein electrophoresis showed no significant change in pre-beta-lipoprotein percent, a significant decrease in alpha-lipoprotein percent and a significant increase in beta-lipoprotein percent after 3 and 15 months (p less than 0.001). Beta-lipoprotein band increased in 50% of DMPA users after 3 months and in 90% after 15 months and the type of hyperlipoproteinaemia was IIa. All calculated atherogenic indices showed significant changes (p less than 0.001) after 3 and 15 months of DMPA use. There was no significant correlation between AT III changes and changes in serum lipids. The study suggests no risk of thrombosis after 3 and 15 months of DMPA use. However, the risk of atherosclerosis appears to be possible as there were significant changes in serum lipids.

Effect of long-acting progestagen-only injectable contraceptives on carbohydrate metabolism and its hormonal profile

Two groups, each composed of 20 women, who used depomedroxyprogesterone acetate (DMPA) or norethisterone enanthate (NET-EN) injectable contraceptives were investigated for changes in 75-g OGTT and in the fasting and two-hour post oral glucose load (2-hours) levels of serum insulin, growth hormone, glucagon, cortisol and blood pyruvate. Samples were taken before and 3, 6 and 12 months after use of injectables. DMPA and NET-EN caused significant changes in mean blood glucose and pyruvate and in mean serum insulin, growth hormone and glucagon, but not in mean fasting cortisol. Changes with NET-EN started after 3 months, became maximal after 6 months and reverted to normal after 12 months of use, due to more frequent administration during the first 6 months of use (every 60 +/- 5 days) and to more spacing of the injections (every 84 +/- 5 days) after that. Changes with DMPA started after 3 months, and increased with the duration of use to become maximal after 12 months. Maximal changes were similar with DMPA and NET-EN and consisted of: a significant increase in fasting blood glucose and pyruvate and serum insulin; a significant increase in 2-hour blood glucose and pyruvate, serum insulin, growth hormone and glucagon. Although significant changes in blood glucose levels occurred with both DMPA and NET-EN, yet they did not reach the lower cut-off levels for impaired glucose tolerance in any user. With the same spacing of injections, i.e. every 84 +/- 5 days for NET-EN and every 90 +/- 5 days for DMPA, the effects on various parameters studied were less with NET-EN.

Levels of serum steroid hormones in intrauterine contraceptive device users

Serum progesterone, estradiol, testosterone and cortisol were assayed in the mid-follicular and mid-luteal phases of the menstrual cycles in 30 Lippe's loop and 30 Cu T-200 IUCD users, compared to 24 controls. Mean serum progesterone and estradiol levels were significantly higher in the mid-luteal, compared to the mid-follicular phase in each group (p less than 0.01). There were no significant differences between the mean levels of progesterone, testosterone and cortisol in IUCD users and controls in both the mid-follicular and mid-luteal phases. IUCD users had significantly higher levels of estradiol (p less than 0.01) in the mid-luteal phase but not in the mid-follicular phase, compared to controls. There was hormonal evidence of corpus luteum insufficiency in 8.3%, 14.3% and 20% in the controls, Lippe's loop and Cu T-200 IUCD users, respectively.

Postpartum colposcopy of the cervix: injury and healing

Colposcopic examination was done in 189 successive parturients within 6-48 h of delivery for evidence of type, site, and extent of cervical trauma and its relation to various obstetric factors. There was trauma in 66% of cases, as erosion in 79%, as laceration in 56%, as bruising in 30%, and as yellow areas in 17%. In about two-thirds of cases, the diameter of cervical erosion, or the length of laceration did not exceed 5 mm and 81% of lacerations were of first degree. Cervical injury was significantly more frequent in primiparae, in the anterior cervical lip, in occipito-posterior positions, and with premature rupture of membranes. In 117 parturients with cervical injury another colposcopic examination was done 6-8 weeks postpartum. In 8% there was residual cervical damage.

Cervical pathology with intrauterine contraceptive devices--a cyto-colpo-pathological study

One-hundred Lippes loop and 100 Cu T-200 intrauterine contraceptive device (IUCD) users, for more than one year, and 200 control non-users were examined clinically, cytologically, colposcopically and histopathologically for associated cervical pathological lesions. Nonspecific infection increased significantly in both Lippes loop and Cu T-200 IUCD users, compared to non-users (P less than 0.05). On the other hand, there was no statistically significant difference in the incidence of total, or individual, specific infections, dyskaryosis or CIN between both groups (P greater than 0.05). Colposcopically, there was a significant increase in inflammatory changes with both Lippes loop and Cu T-200 IUCD, compared to controls (P less than 0.05), but there was no difference in other colposcopic findings (P greater than 0.05).

The reliability and clinical use of a rapid phosphatidylglycerol assay in normal and diabetic pregnancies

Lecithin phosphorus concentration, the standard fetal lung maturity test in our institution, and phosphatidylglyercol were assayed in 69, 29, and 45 amniotic fluid samples from normal (GI), gestational (GII), and insulin-dependent diabetic (GIII) women by means of thin layer chromatography and Amniostat-FLM, respectively. Lecithin phosphorus concentration greater than or equal to 0.1 mg/dl and positive or strong positive Amniostat-FLM results were considered mature. The results of both assays were concordant in 79% of the samples. The discordance rate was highest in GIII patients. In our experience, respiratory distress syndrome did not develop in neonate infants of diabetic women delivered after a mature lecithin result. With lecithin phosphorus concentration as the reference standard, the predictive value of a mature Amniostat-FLM result was 96.2%, whereas that of an immature result was 58.5%. Respiratory distress syndrome occurred in only two GIII neonates who were delivered within 72 hours of both immature lecithin and Amniostat-FLM results. These findings support the use of Aminostat-FLM as a screening test for fetal lung maturity in both normal and diabetic pregnancies. Additional tests will be necessary to evaluate further fetal lung maturity only if the results are negative.

Uterine artery ligation to control postpartum hemorrhage

Bilateral uterine artery ligation was performed for 32 patients in order to control intractable postpartum hemorrhage in 25 of them (currative ligation) and as prophylaxis against postpartum hemorrhage in seven (elective ligation). Mass ligation was used for 29 patients and isolation ligation for three. Among the 25 patients for whom curative ligation was performed, successful hemostasis was achieved in 20 patients (80%) and the technique failed in five (20%). This failure was due to a clotting defect in three and placenta previa accreta in two patients. Twenty-four patients (96%) survived and one died as a result of a clotting defect. Among five patients followed up, normal menstruation occurred with pregnancy in three of them.

Prophylaxis against prostaglandin-induced gastrointestinal side effects

Prostaglandin F2 alpha was administered intravenous drip in 130 patients with missed, incomplete inevitable and septic abortion, intrauterine death and vesicular mole and for therapeutic termination of midtrimester pregnancies. In 84 patients (control group), no prophylactic antiemetic or antidiarrheal drugs were administered, while in 46 patients (study group), an antiemetic (prochlorperazine) and an antidiarrheal (diphenoxylate hydrochloride with atropine sulfate) drug were administered prophylactically before and during prostaglandin infusion. The incidence in vomiting and diarrhea was statistically much less in the study group (P less than 0.0005 for vomiting and P less than 0.005 for diarrhea). There was no statistically significant difference in the success rate of prostaglandin induction in the two groups.